Enhancing exopolysaccharide antioxidant formation and yield from Phellinus species through medium optimization studies

The study was conducted to enhance exopolysaccharide (EPS) antioxidant formation (as measured by Trolox-Equivalent Antioxidant Capacity, TEAC) by Phellinus sp. P0988 through medium studies, while jointly increasing EPS yield. Out of seven medium components, four significant variables were identified based on linear models with statistical significance (p < 0.05), namely rutin, FeSO4, and aspartate, which influenced TEAC, and malt extract, which influenced yield. Based on regression analysis of the experimental results from central composite design in response surface models, two second-order polynomial models adequately representing the relationship between these variables and EPS TEAC and yield were obtained, and the optimum concentration of these variables were determined and validated. Variable combinations for high EPS TEAC and yield were optimized through a desirability function test. The maximum EPS TEAC and yield reached 8.49 ± 0.32 mM and 10.92 ± 0.68 g/L, respectively, in a 7 L bioreactor under the optimum variable combinations.